Method of making fused multifocal lenses



Nov. 5', 1929. c. G, HAERING 1,734,428

KING FUSED MULTIFOCAL LENSES Filed Dec. 1, 1926 INVE NTUR CarlG'Haering. BYKWQ his AT TURNEYS Patented Nov. 5, 1929 UNITED STATESPATENT OFFICE,

OARL G. HAERIN G, OF ROCHESTER, NEW YORK, ASSIGNOR TO BAUSCH'G'c LOMBOPTICAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORKMETHOD OF MAKING FUSED MULTIFOCAL LENSES Application filed December 1,1926. Serial No. 152,021.

This invention relates to fused multifocal lenses, and has for itsobject the provision of a simple and efficient method of making fusedmultifocal ophthalmic lenses.

More particularly, the object is to provide a simple and eflicientmethod of-making fused trifocal lenses and an improved product.

' Other objects will be in part obvious or in part pointed outhereinafter.

The invention accordingly consists in the features of construction andarrangements of parts as will be exemplified in the structurehereinafter described, and the method which will be described, and thescope of the application will be indicated in the following claims.

In the accompanying drawings in which is shown one of the possibleembodiments of this invention,

Figure 1 is a front, or face view of a major lens blank;

Figure 2 is a sectional view of a major lens blank and a'minor lensblank or button in position for fusing;

Figure 3 is a sectional view of a major lens blank showinga disc, orbutton, attached thereto, on the concave side;

Figure 4: is a sectional view of the lens sholwn in Figure 3 after ithas been completed, an

Figure 5 is a view of a completed lens in VYldIlCh the button isattached to the convex 51 e.

Similar reference characters refer to sim ilar parts throughout theseveral views of the drawings.

Referring now to the drawings in detail, 10 indicates a major lens blankprovided on its concave side with curved surfaces 12 and 13. 14indicates a disc, or button, fused on the surfaces 12 and 13; and 15indicates the completed minor lens. In Figure 5 is shown a lens 16provided on its convex side with curved surfaces 17 and 18 and havingattached thereto the minor lens 19. v

In carrying out my invention, I prefer to first grind a countersink ordepression on a face of a major lens blank to provide a surface 12having a desired curvature. I then grind a second countersink on aportion of surface 12 to provide a surface 13 which may have a greatercurvature than the surface 12. These surfaces are ground and polished ina manner well known in the art. The curvatures to which the surfaces areground are determined by the powers desired. A disc or button composedof a glass having a lower melting oint than the glass of the major blankis t ien ground and polished to provide a surface which may be ofsubstantially the same curvature as the surface 13.

The prepared disc or button 14 is then placed over the curved surfaces12 and 13 with one edge portion in contact with the major lens blankadjacent the center of said major blank and the outer edge of the curvedsurface 12, as indicated at 20, and the opposite edge portion spacedfrom the major blank by means of a wire or other suitable spacing meansas indicated at 21. The thickness of the spacing member and thecurvatures of the contacting surfaces are such that there is but asingle point of contact between the major lens blank and the disc orbutton. lVhcn the two members have been suitably arranged they areplaced in a suitable furnace or muffle and heated to a temperaturesufficient to effect melting of the button and fusion of the twomembers. The fusion starts at the contact point and works progressivelytoward the spacing member, filling the concavities or countersinksformed by the grinding of the surfaces 12 and 13 and forcing out all airand gas as it proceeds. When the fusion is complete the composite blankis removed and cooled and finished by grinding and polishing thesurfaces to secure the desired powers.

The index of refraction of the glass of the minor portion or button ispreferably higher than that of the major lens portion.

\Vhile I have shown a major lens blank having a convex surface and aconcave surface, obviously I could use a major blank having a surface ofany curavture on either side.

The completed lens shown has outer portions which provide distant andnear vision fields and an intermediate portion which provides anintermediate vision field, however,

the vision fields may have different relative positions.

From the foregoing, it will be seen that there is herein providedanimproved method which embodies the features of this invention andachieves the objects thereof, and by means of which a new and improvedtrifocal lens is produced.

As many possible embodiments may be made of the above invention, and asmany changes might be made in the embodiment above set'forth, it is tobe understood that all matter hereinbefore set forth or shown in theaccompanying-drawings is to be interpreted as illustrative and not in alimiting sense.

I claim as my invention:

1. The method of making a multifocal lens which comprises formingaplurality of countersinks on a face of a major lens blank, each of saidcountersinks forming a separate vision field, and fusing a single minorlens blank on the surfaces .of all of the counter-' curvature than thefirst curved surface on aportion of the said first curved surface andfusing a single minor lens blank on both of the said curved surfaces. jI

4. The method of making a trifocal lens which comprises providing aportion of a face of a major lens blank with two surfaces of differentcurvatures, placing a single minor lens blank on the major lens blankwith an edge portion thereof in contact with the unaltered portion ofthe major blank and fusing the blanks to form a composite lens.

5. The method of making a trifocal lens which comprises grinding acountersink on a surface of a major lens blank to form a curved surface,grinding a second countersink on a.

portion of the surface thus formed to pro- 1 vide a second curvedsurface, grinding amiwhile thus nor lens blank to provide a convexsurface having substantially the same curvature as the said secondcurved surface, placing the prepared minor blank on the major blank:

with its convex surface adjacent the said curved surfaces and with oneedge portion of said minor blank in contact with said major blankadjacent an edge of the first countersink and an opposite edge thereofspaced from the major blank, and fusing the blanks positioned to form acomposite lens. a 3

6. The process of making a multifocal lens which comprises providing fora vision field a trifocal lens by forming a curved area on a portion ofa major lens blank, providing for a second vision field by forming asecond curved area on a portion of said first curved area and fusing aminor lens blank to the major lens blank tocover both of said curvedareas.

' CARL G. HAERING.

